"It is my considered opinion that in the fullness of time, history will record the greatness of Trimble and it will be recorded at my expense." Ian Paisley, 2009.

THAT adaptation of De Valera's alleged remark in 1966 about Michael Collins was a contribution to a long discussion on the Slugger O'Toole blog last week about David Trimble's decision to join the Conservative Party. Neat idea, but if the Doc ever admits this self-evident truth, I'll ask him if I may eat his fedora.

But what now for Trimble? Well, it's really going to upset his petty detractors, but David Cameron will soon give him a serious job. Welcoming him, Cameron described him as a man of "great judgement and great experience", who would be bringing a great deal with him, "not just on the subject of Northern Ireland, but more broadly on security, terrorism, the constitution and develop[ing] the Conservative Party for the future. It's not every day you can welcome a Nobel Prize winner to your party".

Cameron knows that Trimble has many other qualities: his wide intellectual interests have given him a historical perspective rare in modern politicians; in an age of philistinism, he is an exceptionally cultivated man; and he is a well-respected player on international platforms. And he is widely admired in Britain.

Most of Britain dislikes or loathes the Northern Irish politicians who turn up on television whining, hectoring or threatening, but they like Trimble. They've forgotten those images of him at Drumcree in an Orange collarette: gradually, he's sunk into the public consciousness as generally a good thing. He learned to curb his temper and, indeed, became popular with interviewers because he answered questions calmly, fully, rationally and sometimes humorously.

Among those who follow politics there is a great respect for his physical and moral courage, and a sense that he was a decent person shafted by bigots and terrorists, who sacrificed his career and his party in the interests of the greater good.

For years it's been impossible to walk down a London street or sit in a restaurant with Trimble without being interrupted by members of the public wringing his hand and telling him how brave they think he is. In an age when spin is suspect, he scores for having substance over style.

As far as the Conservative Party is concerned, his recruitment will be very popular. The rank-and-file know he is no carpet-bagger. For years he has been speaking at Conservative Associations around Britain; many senior Tories were impatient for him to join up; and his friends have known for a long time that it was only his grim sense of duty that kept him grinding away in Northern Irish politics when his heart was in Westminster.

That he stuck with the Ulster Unionists until after the assembly elections, out of loyalty to his successor, will have done him no harm with Cameron either.

Unlike most Northern Ireland politicians, Trimble has for a long time wanted Northern Ireland to break away from tribal, sectarian politics.

He was privately highly critical of the Labour Party deal with the SDLP that stopped Labour operating in Northern Ireland and meant that the Conservatives were left shadow-boxing on the sidelines. It took a threat of legal action - backed by the Commission for Racial Equality - to force Labour to allow people from Northern Ireland to join the party: they are still trying to block anyone from standing for election, but will have to cave in soon.

Trimble's move comes at a time when the political classes are deeply worried by current threats to the union. The devolved government in Scotland has been so unpopular that, although there is not much appetite for independence, the desire to punish the Labour/Liberal Democrat coalition makes it likely that the Scots Nationalists will do well in the May elections.

Simultaneously, in England, widespread resentment at high subsidies for Scotland and general grumbling about all the Scots in the cabinet have led to a general feeling that it would be good riddance if the Scots decided to go off on their own. It was, therefore, no surprise that Cameron took Trimble with him to Scotland last week to campaign for the Tories and the union.

When I met Trimble more than 20 years ago, he was a painfully shy provincial law lecturer distrusted in academic circles because of his political connections. I liked him and thought him intelligent, honest and honourable, but I would not have tipped him to become a statesman. But then, no one could have predicted how exceptional is his capacity to grow through experience.

Of all my friends, he has had the most extraordinary career and the most bizarre changes in fortune.